Skip to main content
Updates to LVK & CHIME Notices, Schema v7.2.3! See news and announcements

GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. See the documentation for help with subscribing to or submitting Circulars.

Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
Advanced Search

To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.

Advanced Search Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

24279 results found.

  1. GRB 260226A: LCOGT Optical Upper Limit
  2. GRB 260225D: Glowbug gamma-ray detection of a likely short burst
  3. GRB 260226A: Glowbug gamma-ray detection
  4. GRB 260226A: NuSTAR detection of bright prompt emission
  5. GRB 260226A : GROWTH-India Telescope optical observations
  6. GRB 260226A: Fermi GBM observation
  7. GRB 260226A: Fermi-LAT refined analysis
  8. The EP-WXT trigger 01709258652 is likely a flaring star
  9. LAT GRB260226.44: Global MASTER-Net observations report
  10. Fermi GRB 260226A: Global MASTER-Net observations report
  11. GRB 260226A: Fermi-LAT detection of a bright burst
  12. GRB 260226A???: BALROG localization (Fermi Trigger 793795080 / GRB 260226443)
  13. GRB 260226A: Fermi GBM Final Real-time Localization
  14. GRB 260225A: EP-FXT follow-up observation
  15. GRB 260225A: SVOM/VT optical observation
  16. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) Detection of an Optical Counterpart Candidate
  17. GRB 260225C: Fermi GBM Final Real-time Localization
  18. GRB 260223A: Fermi GBM Observation
  19. GRB 260225B: Fermi GBM Final Real-time Localization
  20. EP260126a: VLA 6 GHz detection
  21. GRB 260225A: SVOM detection of a burst
  22. EP260223a: Xinglong optical upper limit
  23. EP260213a: Mephisto optical upper limits
  24. sb26021801: SVOM/C-GFT upper limit
  25. GRB 260223A: SVOM/VT optical observation
  26. GRB 260223A: SVOM/GRM observation
  27. GRB 260223A: DDOTI Optical Candidate
  28. GRB 260223A: BALROG localization (Fermi Trigger 793512674 / GRB 260223174)
  29. Fermi GRB 260223A: Global MASTER-Net observations report
  30. GRB 260223A: Fermi GBM Final Real-time Localization
  31. GRB 260222A: Fermi GBM Final Real-time Localization
  32. EP260221a: Global MASTER-Net observations report
  33. EP260221a: EP-FXT follow-up observation
  34. Fermi GRB 260221B: Global MASTER-Net observations report
  35. GRB 260221B: Fermi GBM Final Real-time Localization
  36. EP-WXT01709258519: Xinglong optical upper limit
  37. EP260221a: Xinglong optical upper limit
  38. Fermi GRB 260221A: Global MASTER-Net observations report
  39. ZTF26aaglqak/AT2026dbl: COLIBRÍ Optical Observations
  40. GRB 260221A: Fermi GBM Final Real-time Localization
  41. EP260221a: GOTO optical upper limit
  42. SVOM alert sb26021801: LCO optical upper limit
  43. The EP-WXT trigger 01709258519 is likely caused by Mrk 421
  44. IceCube-260217A: Upper limits from a search for additional neutrino events in IceCube
  45. GRB 260219A: GECAM-B observation of a long burst
  46. Fermi GRB 260219A: Global MASTER-Net observations report
  47. GRB 260219A: Fermi GBM Final Real-time Localization
  48. IceCube Alert 260217A: Global MASTER-Net observations report
  49. Fermi-LAT Gamma-ray Observations of IceCube-260217A
  50. GRB 260217A: Fermi GBM Final Localization
  51. GRB 260214B/EP260214b: SVOM/ECLAIRs detection through targeted search
  52. sb26021801: SVOM detection of a long faint X-ray transient
  53. The EP-WXT trigger 01709258455 is likely a flaring star
  54. EP260214b: 1.3m DFOT optical upper limit
  55. Konus-Wind detection of GRB 260212A
  56. IPN triangulation of GRB 260212A
  57. IceCube-260217A - IceCube observation of a high-energy neutrino candidate track-like event
  58. GRB 260216A: Fermi GBM Final Real-time Localization
  59. GRB 260206A: probable hard X-ray burst from 4U 0513-40
  60. EP260214a: Optical upper limits with Kinder observations
  61. EP260214b: EP-FXT follow-up observation
  62. EP260214a / GRB 260214A: Fermi-GBM Sub-Threshold Detection
  63. EP260214b: DDOTI Optical Detection
  64. EP260214b: GROWTH-India Telescope optical upper limit
  65. EP260214b: SVOM/VT optical observation
  66. EP260214a: refined analysis of the EP-FXT observation
  67. EP260214a: SVOM/VT optical upper limits
  68. EP260214a: Global MASTER-Net observations report
  69. GRB 260212A: Fermi GBM Observation
  70. EP260213a: Global MASTER-Net observations report
  71. GRB 260212A: GECAM-B observation
  72. EP260213a: Optical upper limits with Kinder observations
  73. EP260213a: SVOM/VT optical upper limit
  74. EP260213a: NUTTelA-TAO Early Optical Limits
  75. EP260213a: SVOM/C-GFT upper limit
  76. EP260213a: refined analysis of the EP-FXT observation
  77. GRB 260212A: SVOM/GRM observation of a long burst
  78. GRB 260213B: Fermi GBM Final Localization
  79. GRB 260213B: BALROG localization (Fermi Trigger 792697214 / GRB 260213736)
  80. GRB 260211A - SVOM/ECLAIRs refined analysis
  81. GRB 260204A: SVOM/ECLAIRs refined analysis
  82. GRB 260213A: Fermi GBM Final Localization
  83. GRB 260211A: EP-FXT follow-up observation
  84. GRB 260211A: SVOM/VT optical observation
  85. Fermi GRB 260212A: Global MASTER-Net observations report
  86. GRB 260212A: Fermi GBM Final Real-time Localization
  87. GRB 260210A: SVOM/GRM observation
  88. Fermi GBM Sub-Threshold Detection of GRB 260211A
  89. Konus-Wind detection of GRB 260207B
  90. GRB 260128B: SVOM/ECLAIRs refined analysis
  91. GRID detection of GRB 260207B
  92. GRB 260211A: LCO optical upper limits
  93. GRB260131A/B: 3.6m DOT Optical Observations
  94. Fermi trigger No 792537871: Global MASTER-Net observations report
  95. GRB 260211A: SVOM detection of a burst
  96. Swift Operations Update + Community Forum (Friday, February 13 @ 10:00 AM EST)
  97. Konus-Wind detection of GRB 260209B
  98. Konus-Wind detection of GRB 260127B
  99. Fermi GRB 260210C: Global MASTER-Net observations report
  100. EP260210a: Global MASTER-Net observations report

Advanced

Download all Circulars as a .tar.gz archive (updated once a day):
Looking for U.S. government information and services? Visit USA.gov